1. Field of the Invention
This invention relates to stacking amount detection control of a delivery processing apparatus coupled to a recording apparatus and, more particularly, to a delivery processing apparatus accurately detectable of a delivery stacking amount according to sheet delivery modes and to an image forming apparatus having this delivery processing apparatus.
2. Description of Related Art
Image forming apparatuses such as printers conventionally include a delivery processing apparatus for delivering plural image-formed (or recorded) sheets upon processing the sheets such as stapling where each edge is aligned. Such a delivery processing apparatus is formed on a top face or a side face of a sheet delivery outlet side of an image forming apparatus body, and a type of such a delivery processing apparatus has been known as the sheets on which recording is made at the side of the image forming apparatus body, are fed sheet by sheet from the delivery outlet to align each edge and to be delivered upon subjecting to processing the sheets.
Those delivery processing apparatuses tend to be formed with a mechanism detecting a stacking amount of the post-processed sheet bundles, and a control is frequently made as to suppress the sheet delivery to the delivery processing apparatus particularly when the stacking portion is made full.
When the sheet bundles subject to the sheet processing such as a stapling are stacked, however, proper stacking may not be performed due to rising only at the stapled portion. Under such a situation, the stacking amount detecting means located at the stapled portion likely detects as a fully stacked state even though the full stacking is not detected, thereby resulting disturbance of conveyance of the subsequent sheets.
To solve this problem, it may be required to form the stacking amount detecting means at the center as well as at the stapling position. Where stapling is made at an edge of the sheets, however, the stapling position tends to be near the alignment position of the sheet bundles, so that the operation ranges of the alignment mechanism and the stacking amount detecting mechanism inevitably interfere with each other, and so that the image forming apparatus may not operate with proper alignment operation and proper detection of the stacking amount.
This invention is to solve the above problems. It is an object of the invention to provide a delivery processing apparatus accurately detectable of a stacking amount of stacked sheet bundles and an image forming apparatus having this delivery processing apparatus.
A representative structure according to the invention to accomplish the above object is a delivery processing apparatus for delivering sheets after aligning the sheets and processing the sheets in a prescribed manner, characterized in having: an aligning medium including an alignment member operable to align a sheet on the alignment stage and to escape to a home position during a non-alignment period; a sheet conveyor for conveying the sheet on the alignment stage; a sheet processor for performing a prescribed processing to the sheet on the alignment stage; and a stacking amount detecting medium including a detection member selectively moving to a detection position and a non-detection position at a region overlapping an operation region of the alignment member to detect the stacking amount of the sheet delivered to a delivery portion, wherein the stacking amount detecting means operates in a first stacking amount detection mode for detecting a stacking amount of the sheets stacked at the delivery portion during a first delivery mode in which the sheets processed by the sheet processing means are delivered to the delivery portion and operates in a second stacking amount detection mode for detecting a stacking amount of the sheets stacked at the delivery portion during a second delivery mode for delivering the sheet to the delivery portion without executing the alignment operation.
According to the invention, even with the delivery processing apparatus in which the operable ranges of the alignment member for aligning the sheets and the detection member for detecting the stacking amount of the sheets are overlapping to each other, the sheet stacking amount can be detected accurately by changing the detection mode in a case that the sheets are processed and in a case that the sheets are not processed.